The field of the invention is systems and methods for installing fiber optic cable or similar cables or conduits underground. More specifically, the invention relates to the installation of such cable or conduit into pressurized pipelines, such as natural gas pipelines.
With the tremendous growth of the Internet and telecommunications services in general, there has been a commensurate growth in the need to carry larger and larger volumes of data over existing and newly added communication lines. Existing copper-based communications lines, however, have a limited carrying capacity, or bandwidth, as compared to fiber optic cable. Conventional copper wires also suffer from the problem that the wire bundles are quite large as compared to their fiber optic counterparts. Additional copper wires could be installed to increase the overall capacity of a communications or data network. However, fiber optic cable is now preferred within the communications industry due to its significant advantages over copper wires.
Currently, in many countries, there are existing large scale fiber optic backbones that stretch across wide areas. Unfortunately, many businesses and consumers cannot connect to this fiber optic backbone because they are located some distance away from the main line. If copper-based lines are connected to the fiber optic backbone, the high speed and high bandwidth advantages of fiber optic cable are lost. In order to take advantage of the increased speed and bandwidth provided by fiber optic cable lines, shorter segment fiber optic lines need to be laid to reach these businesses and consumers.
Unfortunately, it is a difficult and costly procedure to lay fiber optic cable in developed regions where infrastructure such as roads, utilities, and the like are already in place. For example, it can be costly to obtain the requisite right-of-ways or easements from numerous different property owners. It can also be very costly to dig trenches to lay fiber optic cable. In addition, it is also often necessary to obtain the approval of various state and local government agencies before such work can begin. This can significantly increase the overall cost and delay the completion of the installation.
Existing gas pipelines have been considered as one potential conduit that can be used to carry fiber optic cable. By using existing gas pipelines, there is no need to obtain numerous right-of-ways or easements, since the fiber optic cable simply resides within the pipeline. In addition, long trenches do not have to be dug to lay the fiber optic cable. However, using gas pipelines as a route for fiber optic cable typically requires that sections or all of the pipeline be shut down for an extended period of time for installation of the cable. Even if the gas pipeline is not completely shut down, existing techniques interrupt the normal flow of gas.
In the past, various systems and methods have been used to install cable or conduit in liquid pipelines. These known systems and methods have met with varying degrees of success. However, these liquid pipeline systems are generally not well suited for use in gas pipelines. Providing adequate seals in gas pipelines is typically more difficult and requires sealing techniques which are different from those used with liquids. In addition, as liquids are much denser or heavier than gas, the large current or flow forces available in a liquid pipeline for carrying a drogue or similar devices, are not available in gas pipelines. In addition, the buoyant forces of a liquid pipeline, which can help to center and convey a drogue or conduit line, are not available in a gas pipeline. Hence, installing a conduit or cable into a gas pipeline presents unique engineering challenges. On the other hand, techniques which work for gas pipelines will generally also be useful with liquid pipelines.
Accordingly, there is a need for a relatively quick and inexpensive way of installing fiber optic cable, or conduit which can be used to house the cable, into existing pipelines such as natural gas pipelines.
In a first aspect of the invention, a method of installing cable into a pressurized pipeline includes the step of attaching a first air or pressure lock housing to the pressurized pipeline at a first location, preferably via a first access fitting. A second air or pressure lock housing is attached to the pressurized pipeline at a second location, also preferably via a second access fitting. Duct rod is preferably fed into an entry port of the first access fitting. A rod end guide, such as a guide ball, may be attached to the end of the duct rod via a manipulator within the first air or pressure lock housing or may be attached outside the pipeline. The duct rod is pushed or routed to the second location and guided into the second access fitting.
The rod end guide or ball, if used, is then advantageously removed from the duct rod if necessary via a second manipulator in the second air lock housing. Fiber optic cable or a similar cable or flexible conduit, is attached to the duct rod. The duct rod and the fiber optic cable or conduit are pulled back through the entry port and/or pushed forward through the second entry port. The pipeline is then sealed and the first and second air lock housings may then be removed. In the case of conduit installation, the fiber optic or other cable can be installed using conventional techniques at any time after the conduit is installed.
A second and separate aspect of the invention includes the steps of attaching a first drilling fitting or nipple to the pressurized pipeline at a first location. A first valve is attached to the first drilling fitting. A duct rod is partially inserted into the entry port of the first drilling fitting to seal the entry port. A cutting or drilling tool is attached to the valve, and sealed against the valve. The valve is opened. A pipe cutter of the cutting tool is extended through the open valve to cut or drill a hole into the pressurized pipeline through the first drilling fitting. The drilling fitting and pipe cutter are preferably perpendicular to the pipeline to facilitate the drilling operation. The cutter is withdrawn and the valve is then closed. The cutting tool is removed.
A first air lock housing is installed on the first valve. The valve is opened and the pressure is equalized between the first air lock housing and the pressurized pipeline. A guide ball or similar duct rod end guide may be attached onto the end of the duct rod using a first manipulator in the first air lock housing.
A second drilling fitting is attached to the pressurized pipeline at a second location. The exit port of the second drilling fitting is sealed. A second valve is attached to the second drilling fitting. A cutting or drilling tool is attached and sealed against the valve. The valve is opened. A cutter is extended from the cutting tool and a hole is cut or drilled into the pressurized pipeline through the second drilling fitting. The cutter is withdrawn and the valve is closed. A second air lock housing is installed on the second drilling fitting. The second valve is opened and pressure is equalized.
A duct rod is pushed along inside of the pressurized pipeline and guided into the second drilling fitting. At the second drilling fitting, the guide ball or other rod end guide, if any, is removed from the duct rod with a second manipulator. The duct rod is attached to a fiber optic cable or conduit. The duct rod and the conduit are pulled through the pipeline (either back or forward). First and second completion plugs are installed on the first and second drilling fitting. The pressure is released in the first and second air lock housings. The first and second air lock housings and the first and second valves can then be removed.
In another aspect of the invention, a guide trough can be advantageously deployed using a manipulator in the air lock housing. The guide trough receives the duct rod or conduit and directs the duct rod or conduit through the exit port. The guide trough is preferably designed to provide guidance for duct rod, fiber optic cable, or conduit without changing troughs. The deployable trough and shield are removably stored in the second and/or first air lock housing. The trough may be left in the pipeline permanently. The trough may be perforated to reduce flow resistance. If the trough is not used, the cable, guide rod or conduit can be guided into the exit gland without use of a trough by the manipulator.
In yet another aspect of the invention, a preferably plastic conduit is used in place of the duct rod. The conduit is typically driven by a driving mechanism and enters the pressurized pipeline via the entry port. The conduit may be used in the methods described above, in place of the duct rod. The fiber optic cable is then pushed, pulled or air-blown through the plastic conduit using conventional installation techniques.
In another aspect of the invention, when a cable is directly installed, a mechanism for sealing the cable to the gas pipeline is employed. For conduit, a conduit seal is installed between the conduit and pipeline, and a cable seal is installed between the cable inserted into the conduit (at a later time) and the conduit.
In another aspect, a sail system is deployed in the pipeline. The sail system is lightweight. By occluding almost the entire cross section of the pipeline, the sail system can generate sufficient force from the flowing gas to move the sail system through the pipeline. A lightweight heave line is attached to the sail system and is used for pulling the sail system, and a conduit attached to the sail system, at an exit port, back through the pipeline.
In another separate aspect, a jet reaction nosepiece is attached to a conduit and installed into a pipeline. Compressed gas supplied through the conduit flows rapidly out of rear facing jet nozzles on the nosepiece, helping to propel the conduit forward through the pipeline.
In another separate aspect, the systems, components and methods described for use with cable and conduit are used to install a gas pipe inner duct into an existing pipeline. This provides a new pipeline within the existing pipeline.
The methods and apparatus allow for the installation of fiber optic or other cable, or an inner duct, into pressurized gas pipelines without requiring any shutoff or interruption in gas service. In addition, no bypass pipeline is needed to maintain service to customers connected to the pipe section where cable/conduit is being installed. The methods are suitable for pipelines as small as a few centimeters, and may also be used in both metal and plastic pipelines.
In another and separate aspect, a method is providing for connecting a conduit or cable from a gas main pipeline, through a service line pipeline, to a building. In this method, the service line is first closed off from the main pipeline. First and second fittings are installed in the service line. A service line conduit is preferably routed through the first fitting, the service line, and the second fitting. The fittings are sealed to prevent natural gas leaks after the service line is re-opened to the main pipeline. The service line conduit is sealed to the service line fittings. Bridge conduits are preferably placed between the first service line fitting and the main fiber cable splice connection location and between the second service line fitting and the building fiber splice connection location. A branch fiber cable is then routed through both bridge conduits and the service line conduit.
The invention resides as well in sub-combinations of the methods and systems described. The tools and fittings described also constitute separate inventions to be claimed, apart from systems and methods. These items may also be provided as a kit.
It is an object of the invention to provide a method and system for installing fiber optic or similar cable or conduits into existing pressurized gas pipelines without interrupting the flow of gas in the pipeline.
It is also an object of the invention to provide a method for installing fiber optic cable with use of existing standard fittings, to a large extent, to assist in the deployment and reduce the cost of the fiber optic cable installation.